If you’ve ever had your identity stolen on the Internet, you know how frustrating it can be. I hear stories like this all the time from my students and colleagues: Instead of keeping separate passwords, which you’ve been told to do many times, you decided long ago that one password was good enough to govern all your Internet security. Then, that password is stolen and you’ve lost your identity, money, or access to your personal items. That’s when you wish you had a better way to handle the long list of passwords you need. First, there’s no perfect solution here. You have to stay diligent...